1. Field of the invention
The present invention relates to a process and installation using a free radical oxidation reaction to treat liquid effluents contaminated by at least one organic substance.
2. Brief Description of the Prior Art
The industrial liquid effluents are often contaminated by organic substances such as phenol, benzene, toluene, chloro- or nitro-benzene, methanol, xylene, styrene, and other volatile of halogenated organic compounds. The main sources of such effluents are: treatment/disposal processes for industrial waste waters and liquid wastes, oil refineries and petrochemical plants, pulp and paper mills, foundries and metal refineries, metal/plastic product manufacturing, organic chemicals plants, tanneries, food industry and mineral industry. The numerous, available processes for treating such liquid effluents can be divided into three categories: biological processes, physical processes and chemical processes, A combination of biological, physical and/or chemical processes may also be used.
The efficiency of the biological processes in destroying organic substances can be as high as 97%. However, certain factors such as a concentration of organic matter higher than 500 mg/l or lower than 5 mg/l, and/or a temperature lower than 10.degree. C. may adversely affect the efficiency of such biological processes.
The basic concept of the prior art physical processes is to transfer one organic substance toward another one. These physical processes present two drawbacks: they are selective in the treatment of the liquid effluent, and they require storage and/or disposal of the eliminated contaminants.
The chemical processes use conventional oxidation agents such as chlorine, chlorine dioxide, potassium permanganate, hydrogen peroxide, ozone, ultraviolet radiations, sulphite ions, etc. They are often limited in regard of the volume of liquid effluent to be treated. A prior art process is characterized by a wet oxidation with air, without flame, and is restricted by severe operation conditions: pressures of the order of 3,000 kPa to 300,000 kPa.